The present invention relates to a method and apparatus for making stators for electrical machines. More particularly, the invention relates to improvements in a method and apparatus for converting annular metallic stator blanks into finished stators.
It is known to assemble a stator from a package of laminae which are riveted or otherwise rigidly secured to each other to form a blank ready for treatment of its internal, external and end surfaces so as to convert the blank into a finished stator. It is also known to make a stator blank from a sheet metal strip which is wound edgewise and whose strata are secured to each other prior to machining for the purpose of converting the blank into a finished stator. As a rule, the converting operation involves a preliminary smoothing before the blank is mounted on a mandrel of a first machine tool so as to allow for the machining of its peripheral surface and both end surfaces, i.e., to determine the ultimate outer diameters and axial length of the product. In the next step, the semifinished product is mounted in a second machine tool which engages its peripheral surface and treats the internal surface with a honing tool to determine the internal diameters of the thus obtained finished stator.
A drawback of the just described procedure is that the conversion of a blank into a stator involves at least three discrete machining operations with attendant losses in time, high initial cost and excessive outlay for machine tools. Moreover, repeated clamping of the blank (first on a mandrel and thereupon in a honing machine) often results in pronounced misalignment of the axes of internal and external surfaces of the stator.